VIRTUAL IMAGE THEATER PRODUCTION SYSTEM

Abstract: An apparatus for providing optical illusion effects comprising: a stage area (28) disposed between a rear projection screen (20) and a viewing area (26); a variable illuminating system (30) for the stage area; a partially inclined silvered mirror (32) positioned between the viewing area and the stage area; a second projection screen (34) positioned above the inclined mirror and parallel to the plane of the stage area; a first projection means (38) for projecting images on the rear projection screen; a second projection means (40) for projecting images on the second projection screen so that images can be viewed from the viewing area via the inclined mirror; means (42) for changing between images from the projection means so that viewers may be presented an image from either or both projection means at any one time.

Description: VIRTUAL IMAGE THEATER PRODUCTION SYSTEM BACKGROUND OF THE INVENTION Field of the Invention This invention relates to an apparatus and methods for creating visual illusion effects, and more particularly for creating stage effects in a theater setting. Description of the Related Art Persons who have been involved in attempts to create visual illusions in the live stage productions of plays or other performances have utilized numerous types of devices to create a diversity of visual illusions. Of particular interest are illusions created by visibly merging actors or objects on a stage with a motion picture film to the degree that the observer cannot distinguish between the film and the stage and cannot tell where the boundary is. One technique which has been used involves use of a slit screen. An actor walks on the stage through a flexible slit in a screen on which a motion is being presented. This technique is difficult to make appear realistic because the audience can generally see the slit itself and understand what has actually happened even though various efforts have been made to mask the slit visually, for example, with lights. Thus, despite use of techniques to minimize the visibility of the slit, it remains visible to anyone who sees it done more than once, and there is not a seamless merger of the real object and the projected image. Also of interest are illusions in which a performer appears to be altered or hidden from view while being actually present on the stage. The basic invisibility effect can be achieved by any half-silvered mirror room or box with neutral or regularly patterned background. An early technique known as "Pepper's Ghost" was developed in the nineteenth century and is used in certain illusions of a haunted house. This technique uses an angled piece of glass between the audience and a stage surface. A ghost figure located off-stage where it is not visible from the audience is illuminated with bright lights so that the image of the ghost figure is reflected as a transparent image off the glass. Because of the angle and position of the glass, the transparent ghostly image of the ghost figure appears to be on stage with the "real" characters. Thus, using this technique an object may appear to be become more or less transparent, but it does not ever appear completely solid. Another method of making a character present on the stage seem to disappear, termed "metempsychosis", utilizes a mirror having variations across its surface in the amount it is silvered. For example, lines are scribed in the silvering on a standard mirror, beginning with spread-out and/or thin lines and gradually increasing the thickness of the lines and/or decreasing the spacing between the scribed lines until there is an area of plain glass from which all of the silvering has been removed. The piece of variably silvered glass is placed in a grooved track at an angle across the stage. When the glass is moved back and forth in the track, a person on the stage behind the glass is visible when there is little silvering present between the person and the viewers, and is hidden when there is dense silvering present. The illusion appliance of Hammond (U.S. Patent No. 1,456,233) utilizes a transparent glass mounted on an inclined plane, a translucent screen having a scene on it and positioned above the glass and reflected on it, and a second translucent screen upon which a moving picture may be projected. The moving picture appears to take place on the scene reflected in the glass. Hammond does not provide any mechanism for a live production or the use of actors in conjunction with a moving picture. Other methods have involved partially silvered mirrors, which are typically made by spattering, or otherwise applying platinum or other metal to a glass so that a portion of incident light is reflected and a portion of the light passes through the glass depending on the extent of silvering. Rogers (U.S. Patent No. 4,736,214) provides an apparatus and method for producing what were called three-dimensional images from two-dimensional sources. This invention utilizes a projection source projecting multiple images to spaced apart reflectors, one of which reflectors is reflective and the second of which is transmissive. The invention utilizes two partially transmissive reflecting members and a rotating stage for props. The invention produces two virtual images which are in parallel spaced relation with each other, but does not utilize any images projected on a real screen, nor does it provide a way to used phased image projection coordinated in real time with live action on a stage. A second patent of Rogers (U.S. Patent No. 4,805,895) is for an image forming apparatus and method where there are no image forming surfaces. A false ceiling separates a motion picture projector and rear view projection screen from the audience viewing area. A semi-transmissive reflecting member is disposed at an angle of 13.5 to 31 degrees to a vertical plane in front of the line of sight of the viewing audience. As with the first patent of Rogers, this patent does not provide coordinated real time phasing of images with an actual stage or an actual screen. The Rogers patent also provides a summary of three prior "Blue Room Techniques" utilizing partially silvered mirrors. In the traditional Blue Room the mirror is vertical but at a 45° angle to a plane normal to the axis of a central observer's line of sight to a stage. The real object is in the wings of the theater. In Disney's Haunted Mansion Configuration (essentially the same as Pepper's Ghost discussed above), a large percentage silvered mirror is placed vertically at a 90° angle to a plane normal to the axis of a central observer's line of sight to the stage. The real objects are placed either above or below the audience area. In the Sideways Blue Room, the traditional Blue Room setup is rotated 90° around the axis of the central observer's line of sight. The patent of Robley et al. (U.S. Patent No. 5,061,061) provides a "front projection composite photography system" using reflex screens, and two projected background scenes. This system optically positions a staged scene into a projected scene using the depth characteristics of the camera and perspective introduced by a movable camera and relative camera axis positions of the background projections. The actual registration of the two projections can be viewed and corrected through the camera viewfinder before the particular composite picture is taken. Robley does not include a live performance, nor provide a way that a live stage production using multiple mirrors could be viewed directly by an audience, nor a way of phasing multiple images. It is therefore an object of this invention to provide an apparatus and method for producing virtual image theater, in which there is coordinated real time control over image projection and illumination of a live stage production so that a live audience may be presented a variety of visual illusions during the production. It is a further object of this invention to provide an apparatus and method for providing optical illusion effects, including the illusion that an object or character on a stage has disappeared, or is in a selected position on a stage with respect to projected images. It is a further object of this invention to provide an apparatus and method which utilizes invisibility to achieve merger of stage and screen images through coordination of the degree of transparency of the stage object with the appearance and disappearance of screen images. Other objects and advantages will be more fully apparent from the following disclosure and appended claims. SUMMARY OF THE INVENTION The invention herein is an apparatus and method for creating virtual image theater through the presentation of optical illusion effects. The apparatus includes a first projection screen (which is preferably a rear projection screen) having a front viewing side and being positioned in a first plane; a viewing area from which persons may view said first projection screen; a stage area between said viewing area and said first projection screen; an illumination system for said stage area so that objects on said stage may be illuminated at a desired light level without illuminating said first screen at the same level; an inclined partially silvered mirror between said viewing area and said stage area; a second projection screen positioned in a second plane at a first angle to said first plane, wherein said inclined mirror is positioned between said first and second planes; a first projection means for projecting images on said first projection screen so that images on said first projection screen may be seen by viewers in said viewing area; a second projection means for projecting images on said second projection screen so that images on said second projection screen are visible to said viewers by means of reflection from said mirror and appear to be located at a selected location; and a means of changing between images from said projection means so that viewers may be presented an image from either or both projection means at any one time. The invention further provides a method of achieving visual merger of stage and screen images, to produce a "virtual image" by providing a moving picture which appears to be in a particular location, utilizing one of said projection means. A "virtual image" is an image seen in a mirror. Objects and persons on the stage may be made to appear to change between being in the moving picture and not being in the moving picture, through coordination of the degree of transparency of the stage object with the appearance and disappearance of screen images, by selectively utilizing the projection means and lighting means. The invention may be utilized for entertainment performances, educational and other displays and interactive productions, where objects and/or persons on the stage area act in a manner coordinated with image projection to create a desired effect. Methods of using the apparatus include providing the optical illusion of having characters and objects appear to move from the stage into the screen and vice-versa, allowing interactions between the screen images and objects and/or persons on the stage, and having a character or object on the stage disappear, or having added objects or characters at selected locations with respect to projected images. Other aspects and features of the invention will be more fully apparent from the following disclosure and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of an apparatus according to the invention utilizing one partially silvered mirror and showing how the location of a second projection screen may be changed. Figure 2 is a schematic diagram of an apparatus according to the invention utilizing one partially silvered mirror and a fully silvered mirror. Figure 3 is a schematic diagram of a small scale version of the apparatus using video monitors as the projection screens. Figure 4 shows how a position sensor may be used with the invention. Figure 5 is a schematic diagram of a side view of the apparatus according to the invention. Figure 6 is a schematic perspective diagram of the apparatus according to the invention. Figure 7 is a schematic diagram showing the use of three screens in the invention. Figure 8 is a schematic diagram showing a monitor as part of the invention. Figure 9 is a schematic diagram showing use of a camera to assist in monitoring the stage view for the actor(s) on stage. Figure 10 is a schematic diagram of one possible alternate stage area which may be part of the invention. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF The invention provides an apparatus and method for merging stage action with a projected image for viewing by a live audience. The present invention in . its first embodiment comprises an apparatus for providing optical illusion effects, comprising: (a) a first projection screen 20, most preferably a rear projection screen, having a front viewing side 22 and being positioned in a first plane 24; (b) a viewing area 26 from which persons may view said first projection screen 20; (c) a stage area 28 between said viewing area 26 and said first projection screen 20; (d) an illumination system 30 for said stage area 28 so that objects on said stage are 28 may be illuminated at a desired light level without directly illuminating said first projection screen 20; (e) an inclined partially silvered mirror 32 between said viewing area 26 and said stage area 28, said mirror 32 being inclined upward away from the viewing area 26; (f) a second projection screen 34 positioned in a second plane 36 at a first angle a to said first plane 24, wherein said inclined mirror 32 is positioned between said first and second planes; (g) a first projection means 38 for projecting images by rear projection on said first projection screen 20 so that images on said first projection screen 20 may be seen by viewers in said viewing area 26; (h) a second projection means 40 for projecting images on said second projection screen 34 so that images on said second projection screen 34 are visible to said viewers by means of reflection from said mirror 32 and appear to be located at a selected location; and (i) a source of video images for the projection means and a switching means 42 (most preferably computer-controlled) for changing between images from said projection means 38, 40 so that viewers may be presented an image from either or both projection means at any one time. The invention preferably utilizes a partially silvered mirror, for example, a half-silvered mirror between the viewing area and the screen as mirror 32. Although termed "silvered", other reflective metals may be used. Both sides of such mirrors reflect light, although one side of the mirror provides a clearer, sharper image, and is the side which is used in the invention to reflect images which are to be seen by the audience. A partially silvered mirror as used in the invention may also be termed a "beam¬ splitter" which more graphically defines its capability of allowing a portion of the impinging light to be transmitted, and a portion to be reflected. For a full life-size stage, the size of mirror 32 is preferably at least about 2 x 3 feet for partial views of an actor or views of a small object, to 4 x 6 feet for more substantial views. Preferably mirror 32 is at least about 7 x 12 feet in size so that an actor on the stage behind mirror 32 is not visible to the audience except through mirror 32 when appropriate lighting is used. Larger pieces of course, while being more expensive, and difficult to install, provide the capability of a larger stage area 28 upon which illusions may be provided according to the method of the invention. Thus, any mirror 32 which is of a technologically feasible size may be used. Mirrors may also be joined or mounted side-by-side to extend the mirror area. Preferably, there are opaque side pieces 54 as shown in Figures 5 and 6 on each side of mirror 32. The side pieces 54 both serve as supports for mirror 32 as well as disguising the fact that there is a mirror present by hiding the side edges of mirror 32. Alternatively, scenery pieces may be positioned at the edges of mirror 32 to serve the same purpose. If there are no side pieces 54 or substitutes therefor, extra care needs to be taken with respect to placement of the audience and the actors or objects behind mirror 32 so that a portion of the audience does not see more than is desired. The first projection screen 20 preferably is the size of all or substantially all of the entire rear wall of the stage area 28, however, smaller areas may be selectively covered, particularly if the area in which illusions are to be provided does not comprise the entire stage area 28. To enable the visual merger of stage and screen, first projection screen 20 is a rear projection screen. As shown in Figures 1-3 and 5-6, the second projection screen 34 is preferably positioned above the stage area 28. In this embodiment, for projection of an illusory image that appears to be on the first projection screen 20, the second projection screen 34 is located at the same angle a to the inclined, partially silvered mirror 32 as is the first projection screen 20. Although angle a is preferably 45 degrees and the two projection screens are preferably at a 90-degree angle to each other, other arrangements may be used. The main requirement is that the first projection screen is visible to the audience, and the image from the second projection means may be projected on mirror 32 so that it appears to the audience to be in the location desired for the particular optical effect. Additional projection screens may be added to increase the diversity and complexity of the visual presentations and illusions. The image is projected on to the second projection screen 34, either directly as shown in Figure 1 by rear projection with a video projector in which the image is electrically reversed, or by projection of the image on a fully silvered mirror 44 inclined as shown in Figures 2 and 5-6 and at the same angle as the partially silvered mirror 32. Either of these techniques allows the same background as is being shown by the first projection means 38 to appear to be shown on the first projection screen 20 by the second projection means 40 which allows the method of the invention of making an object or person disappear. Using these techniques, the images seen by the audience as apparently appearing on the first screen may be either projected directly on the first screen or from the second (or third) screen via the first mirror, so that in either case, the screen positions are aligned so that the respective images are apparently identically positioned so that to the audience the images appear to be behind the stage area. Thus, when the first projection means shows a picture, a viewer 46 in the viewing area 26 sees the actual projected images through the partially silvered mirror 32 on the first projection screen 20. When the two projection screens are equidistant from, and at the same angle to, the inclined mirror 32, and the second projection means 40 shows a picture on the second projection screen 34, the image is really reflected in the partially silvered mirror 32, but because of the angles and distances between the screens and mirror, appears to a viewer to be on the first projection screen 20. The projection screen which is not in use is preferably darkened to create either a solid image (use of rear screen and side lighting) or make the image vanish completely (use of top screen only). Thus, when the rear screen image is projected, a person on the stage is visible to the audience as being clearly in front of the rear projection screen, but when the second or third screen image (see discussion of third screen below) is projected, an identical virtual image appears to be in the same spot as the rear projection screen, without being obscured by the person on the stage, and because the person on the stage is no longer illuminated, the audience just sees the virtual image from the second or third screen but does not see the actor even though the actor is still present. The use of both an upper and a lower (rear projection) screen creates a transparent object on the stage as opposed to a solid or vanished object. To the extent the angle at which the partially silvered mirror 32 is hung or positioned creates mirror sag due to bending of the large sheet of glass, specially ground lenses may be used in the top projector to compensate optically for the sag. Alternatively, video projectors known in the art which are capable of correcting for screen sag can be used. A third projection screen 56 and associated third projection means 57 may be placed as shown in Figure 7. In order to make complete use of second screen 34 and third screen 56, second partially silvered mirror 58 (beam splitter) replaces mirror 44 so that the image from one of the screens (shown as second screen 34) may be reflected from mirror 58, while the image of third screen 56 may pass through mirror 58 and be reflected from mirror 32. These two screens may be used in pre-selected sequence to provide virtual images at selected locations with respect to the stage area and the first (rear) projection screen 20 through computer-controlled switching of which screen images are being projected, the movement of the screens, and the lighting on the stage area, using computer- controlled switching means 42. Computer-controlled switching is well-known in the art, particularly for multimedia switching routinely used in many state-of-the- art theaters. Although in theory this process of adding beam splitters (mirrors) and screens, with corresponding projection means could be multiplied indefinitely, because the intensity of the image is decreased with a partially silvered mirror, the intensity of light actually reaching the lower area, and being visible to the audience as a virtual image, decreases substantially (by half when 50% silvered mirrors are used) for each beam splitter the image must pass through or reflect off. To add variety to the number of effects possible with the invention, one or more alternate stage areas 68 may be added (Figure 10). Solid objects and/or actors on an alternate stage, while not directly visible to the audience, can be made to seem to be present on the stage using mirror 58 to reflect the image of these objects and/or actors down to mirror 32, and thence to be viewed as a virtual image as discussed for viewing of images on the second and third screens. Additional illumination means 70 are provided for the alternate stage areas 68. When an alternate stage area 68 is used, it is likely that the first projection screen 20 would be moved back (farther from the viewing area 26) so that the image of an actor on the alternate stage area 68 would be in front of the first projection screen 20. The viewing area 26 is preferably shaped and of a size so that persons in the audience can see the images reflected in mirror 32 at the appropriate time, and also can see an actor or other selected object(s) through mirror 32, when the actor or object are positioned on the stage behind the mirror and appropriately illuminated. This means that the ideal shape for the viewing area is a fan shape as shown in Figure 6. Thus, the audience members should be positioned so they cannot see the stage area behind mirror 32 except by seeing it through mirror 32. Substantially smaller mirror pieces than the large mirror 32 shown in the Figures 1 and 2 may be used for viewing of particular performances, for example, by puppets or smaller acting entities (Figure 3). Monitor 48a is shown for convenience in Figure 3 as being located beneath monitor 48b, closer to the viewer than is optically correct, and would be located substantially to the left of the position shown in Figure 3. For such miniature systems where the partially silvered mirror 32 is of a substantially reduced size, each projection means may comprise a television monitor 48a, b. To provide the different images, a video switcher connected to a video source machine may be used, manually, or by computerized control, to play the selected video either on the first television monitor 48a, or on a second television monitor 48b positioned at the same relative position as the second projection screen 34 of the full-sized version of the invention. Thus, the video source provides an image to the selected monitor, which selection determines whether the image will actually be on the screen which is being viewed by the viewer(s) or will only appear to be on the screen (use of the second monitor and inclined partially silvered mirror). It is clear that in order for the image from the second monitor 48b to match the image from the first monitor 48a, an image reverser would be required if there is no fully silvered mirror 44. The source(s) of the video image(s) may be integrally included in the video switcher 42 or be one or more separate instruments which are connected to both projection means. Lighting on the stage changes in conjunction with the switching between projection means. Thus, when the first projection means 20 is used, lighting from lights 30 placed at one or more of the sides (not shown), top and bottom areas directly illuminates characters and objects on the stage area 28, but. preferably does not in any significant way illuminate the first projection screen 20 or cause light to fall on the first projection screen 20. When the second projection means 40 is used, the characters and objects which are not to be seen are not illuminated directly, and preferably there is little incident light illuminating these characters and objects. Use of low lighting on an object when the second projection screen 34 is used allows an object to be seen as "transparent" as the audience can see the object but can also see what appears to be the background behind the object. If only the second projection screen is used with a side-lit object or person on the stage, the stage object will be very thin and "ghostly". The use of the first projection screen at the same time with a low projection level yields a more defined but still transparent stage object. Thus, the method of the invention allows a wide range of imagery, and a greater sense of presence than the prior art even for its "ghosts". Utilizing selective lighting on particular objects or characters it is possible to have some of the characters or objects disappear and others remain, or to have some objects or characters partly disappear or partly be transparent, as the images switch from being displayed on the first projection screen 20 to those displayed on the second projection screen 34 which are seen by the viewers in mirror 32. Most preferably the area of the selective change is masked on both the first and second projected images to enhance the visual effect. Thus, an area of the image on the first screen, behind the object or character, must be blacked out in the making of the film or the tape or in the projecting of it. At the same time, everything on the second screen except the selected area must be blacked out so that there is an overlaid projection only in the selected area. This transition must be accompanied by a reduction of direct lighting on the selected object or character. In order for the method of the invention to allow a person or object on the stage area 28 to seem to disappear, it is important in the preferred use of all of the embodiments of the invention that the components of the invention are properly aligned optically as discussed above for the first embodiment. Thus, when the particular screens which are being used are aligned, the background seen by the audience remains the same no matter which screen is being viewed because the two images from the two projection means are completely identical in appearance and apparent position to the viewers. When image projection is switched between two or more of such aligned projection screens, phasing of the images occurs, and the audience cannot tell that the switch has occurred because of the synchronization of images. If the components of the invention are arranged correctly, persons in the viewing area 26 are not actually aware that the partially silvered mirror is there. It is important therefore not to dispel this illusion by having bright lights in the viewing area which might be directly reflected off of the mirror surface, or, except as planned for particular events, to allow persons from the audience into the stage area. Also, appropriate curtains or baffles 52 need to be used to hide the second projection screen 34 from the audience. The switching between projection means, and concomitant control of the lighting can be controlled manually for creation of simple disappearing acts or other illusions. For more complicated scenarios, however, it is preferred to provide a computer-controlled switching means 42 comprising computer control of the lighting and projectors as needed for the particular performance. Such switching involves alternately turning on one projector and turning off the other, while also turning lights on or off, as well as controlling the level of variables, such as light, as described herein. Computer-controlled coordination of light control, image production, and screen movement allows phased movement so that various effects can be orchestrated and actor(s) and/or object(s) on the stage can be made to change in transparency, and relative location with respect to a scene or action being projected for viewing by the audience. As used herein, the term "image production system" includes the projection components allowing projection on the screens present in the invention, as well as computerized control over which of the screens is being utilized and the pattern of screen utilization (e.g., the sequence and timing of projection as computer-coordinated with stage lighting and screen movement which are timed in relationship to the action on stage) . In a second more preferred embodiment of the apparatus of the invention, the plane of at least one, and preferably all, of the projection screens is movable. The primary reasons for being able to move the projection screens, particularly during a stage performance, are: (a) to provide the two distinct effects of sandwiching/layering of images and the phasing of images (gradually increasing in visibility of one set of images on one screen, and the gradual reduction in visibility of another identical set of images on another screen); and (b) to be able to move a particular image or series of images as the screen moves so that the image moves through three dimensions. With use of a moving screen an image can be transferred from one screen to another, for example, during a performance, by (a) moving a first screen, on which a series of images of images is being projected, so that the images seen by the audience appear to be in a particular location, and (b) then projecting the same images on another screen which is located so that the images then seen by the audience are in the same location as the images from the first screen had been. This type of movement allows many effects in which an actor or object on the stage can appear to merge with the images. For example, the screen movement can make it appear that something which was clearly in front of an actor has gone around behind the actor. A possible area of screen movement is shown schematically in Figures 1 , 2 and 4 for the second projection screen 34. Each movable projection screen is movable to one or more planes parallel with the plane on which it is positioned. As shown by the dotted lines parallel to the second projection screen 34 in Figure 1, if the second projection screen 34 is lowered from the original second plane 36 to a lower plane P 2 , the apparent screen upon which the viewers see the image is shifted forward to screen position S 2 (shown at an exaggerated distance from the first screen in Figure 4 to allow for the standing person). Although this is not diagrammed specifically for the first and third projection screens, these are also preferably movable in the same manner as shown for the second projection screen 34. Generally, unless other specific effects are desired, it is preferred that the appropriate projection means be moved the same direction and amount corresponding to any movement of a projection screen so that there is not an apparent change in size of the projected image. The opposite effect of shifting the apparent screen position backward away from the viewers occurs if the second projection screen (and preferably the second projection means) is raised above the second plane 36. This illusion occurs even though what is actually being seen by the viewers 46 in all cases when the second projection means 40 is being utilized is a reflection from the silvered mirror 32 which has not changed locations. It is clear that similar movement of the first projection screen in parallel with the position shown in the Figures allows variation of the amount of space between mirror 32 and the first projection screen. The means of movement of one or both projection screens may be by any means known in the art, for example, a bar placed at each of the four corners of the projection screen(s) along which the appropriate screen may track to the selected position. The movable projection screens is preferably motorized so that they can move automatically, using programmed control mechanisms in coordination with other visual effects. Thus, using the second projection screen 34 in a sequence of different positions allows creation of the illusion that the projected image is moving forward or backward as the second projection screen 34 is moved downward and upward, respectively. If this illusion is used, for example, in conjunction with an actual actor on the stage area 28, and in conjunction with the appropriate changes in lighting, a character who is part of the image projected with the second projection means 40 could be made to appear to move, for example, around in front of the actual actor on the stage area 28. In contrast, the use of the rear (first) projection screen 20 allows the image to move behind the person on the stage because the person is between the projected image on screen 20 and the audience. Another type of visual illusion may be created with the apparatus of the method if a position/orientation sensor such as the Polhemus tracker (Polhemus Labs, Cambridge, VT) is also used, for example on the hand of a character on the stage. Use of one or more position sensors provides a method of obtaining feedback as to where the actor is, so that the projected images may be correctly positioned on the screen(s) in relationship to the position of the actor. For example, as shown in Figure 4, if the character paints a name or word in the air by moving the hand appropriately to which the sensor 50 is attached, information from the sensor 50 can be fed back to a computer control mechanism (for example, as is used with such trackers in virtual reality applications) so that the word the character writes will . appear on the second projection screen 34. The location of the second projection screen 34 determines where what is being written will appear to be with respect to the location of the character, for example, in front of or behind the character. Thus, the character may appear to be writing in a plane which is between the first projection screen and the viewing area. Use of this embodiment of the method of the invention would be extremely difficult to do by choreographing the movement of the actor's hand to an image in three-dimensional space because the actor cannot see the image and extremely close registration of the image and movement would be required for the effect to be realistic. Thus, the position sensor allows the actor's movement to be exactly synchronous with the image seen by the viewers. In another example of use of a position sensor 50 with the invention, a character in the stage area 28 could draw the outline of a person in an area defined by where the second projection screen appeared to place the outline, for example directly in front of the character. Using computer graphics the animated picture of a person could appear within the outline drawn by the character. If the real person depicted within the outline were actually present on the stage but had been previously invisible to the viewers 46 using the method of the invention described above, the real person could then be made to become visible to the viewers and to "walk out of" the outline and be on the stage. Use of a positional tracking means, such as a position sensor (or magnetic or optical tracker or visual tracking by someone in the audience) is useful for any type of interactivity of an actor who is in the stage area 28, particularly of a moving actor, with images being projected. The tracker allows closer synchronization and coordination of the actor's movement and location with the location and timing of the images being presented. In order to increase the accuracy of merger between the real and projected images in a live performance, the invention further provides a means to give a performer on the stage area visual feedback, so that the performer can see the virtual images being seen by the audience (Figure 8). Thus, the invention preferably also comprises at least one lower monitor screen 60 which reflects off the rear side (lower) of mirror 32 so that the performer sees a virtual image 66 apparently hanging in space at about the plane of the opening of the front of the stage (the proscenium arch) . This virtual image may be simply a view of the image projected by the top (second and/or third) projector(s) or it may be a composite of these together with what is actually being projected on the rear (first) projection screen at the back of the stage. An alternate version of the monitor screen allows a camera 62 to record stage action including that of the performer, and to electronically composite all images into a representation of the image seen from the audience (Figure 9). The camera 62 is placed below the level of the stage area below mirror 32, and monitor screen 60 is lowered as shown in Figure 9, and an additional lower mirror 64 is utilized. What is happening on the stage is reflected downward from mirror 32 through an opening in the stage floor to mirror 64, and thence to the camera 62 (dotted line). In this way the performer is looking directly out into the audience but seeing exactly what they are seeing and thus is able to act out appropriate actions and emotions. Other possible variations on the invention herein include use of interactive video as the image being projected on to the screens. For example, with interactive video, a person on the stage area can pick up, move or carry a projected image such as a chair or baby. Thus, what the character(s) are doing on the stage interacts with the specific aspects of the screen image, and the script for the program preferably incorporates the optical illusions according to the invention within such interaction. The same effect can be achieved without interactive video using tight choreography of the object and screen images and manual control. Interactive video simply provides a method of achieving better control and tighter timing, and thus provides more sophisticated and complex stage-screen interactions. Producing images directly with a computer allows the creation of images that can be made to react to the actions of the actor(s) in real time. Although the preferred use of the components of the invention involves use of actor(s) and/or object(s) on the stage, and visual merger effects of these with the screen images, it is within the scope of this invention to use the apparatus of the invention without stage action or objects. In this case, the "stage area" is simply the area between mirror 32 and first projection screen 20, and the effects viewed by the audience are determined by the use of projected images and screen location without interaction with actual objects or persons. Whether or not actors or other objects are present on the stage area 28, the apparatus of the invention may be used to provided multiplanar images, rather than a series of projected uniplanar images, so that more than one screen image is being projected and is visible at the same time to viewers who are in the viewing area. This may be accomplished by moving one or more screens so that images projected therefrom are not aligned. In use of the invention herein, it is preferred that a sound system, known in the art as a three-dimensional sound system, be used that makes sounds appear to come from specific locations. The use of such a sound system is thus used to increase the audience's perception that the visual illusions are real. While the invention has been described utilizing video projection, synchronized film projectors may also be used in the apparatus and method of the invention. Preferred embodiment of the Invention The preferred apparatus of the invention for providing visual illusion effects, comprises a first screen which is a rear projection screen, has a front viewing side, and is positioned in a first plane; a viewing area from which persons in an audience may view images on said first screen; a stage area between said viewing area and said first screen; a first inclined, partially silvered mirror between said viewing area and said first screen; a second inclined, partially silvered mirror; a second screen not visible from said viewing area and movable between a plurality of second parallel positions so that a second series of images on said second screen is visible to said persons in said viewing area when said second series of images is reflected on said second mirror and then reflected on said first mirror, wherein said second series of images appears to said persons to be located at a selected location which is determined by the position of said second screen; a third screen not visible from said viewing area and being movable between a plurality of third parallel positions so that a third series of images on said third screen is visible to said persons when said third series of images is transmitted through said second mirror and reflected on said first mirror, wherein said third series of images appears to said persons to be located at a selected location which is determined by the position of said third screen; an image production system, for selective production of: a first series of images on said first screen so that said images are visible on said first screen to persons in said viewing area, and so that objects in said stage area do not cast shadows on said first screen; a second series of images on said second screen; and a third series of images on said third screen; an illumination system for said stage area for selective illumination of stationary or moving objects located on said stage area; a computer-controlled switching apparatus for selectively activating said image production system and said illumination system, and for causing said second and third screens to move; wherein objects and actors actually located on said stage area may be made to appear more or less transparent and to be located in different locations with respect to each other and said first screen and said viewing area, by synchronized coordination of: movement of said second screen and said third screen, selective production of series of images, and activation of said illumination system. The preferred method of the invention, comprises providing the above apparatus, placing one or more objects on said stage area between said partially silvered mirror and said first screen; and utilizing said switching apparatus to coordinate movement of said screens, activation of said image production source to produce images on one or more selected screens in a determined sequence, and illumination of said objects and actors. Industrial Applicability The invention may be used for entertainment and educational and training purposes. While the invention has been described with reference to specific embodiments thereof, it will be appreciated that numerous variations, modifications, and embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention.

Claims: THE CLAIMS What Is Claimed Is: 1. An apparatus for providing visual illusion effects, comprising: (a) a rear projection screen having a front viewing side and being positioned in a first plane; (b) a viewing area from which persons in an audience may view said rear projection screen; (c) a stage area between said viewing area and said rear projection screen; (d) an illumination system for said stage area for illumination of objects on said stage area at a desired light level without directly illuminating said rear projection screen; (e) an inclined, partially silvered mirror between said viewing area and said stage area, said mirror being inclined upward away from the viewing area; (f) a second projection screen positioned in a second plane at a first angle to said first plane, wherein said inclined mirror is positioned between said first and second planes and at equal angles to said first plane and said second plane; (g) a first projection means for projecting images on said rear projection screen so that images on said rear projection screen are visible to viewers in said viewing area; (h) a second projection means for projecting images on said second projection screen so that images on said second projection screen are visible to said viewers by means of reflection from said mirror and appear to be located at a selected location; and (i) a source of video images for the projection means and a computer-controlled switching means for changing between images from said projection means to present to viewers an image from either or both projection means at any one time. 2. The apparatus according to claim 1, wherein said mirror is approximately half-silvered. 3. The apparatus according to claim 1, wherein at least one of said screens is movable. 4. The apparatus according to claim 3, wherein said second screen is movable during performance on the stage area to at least one alternate second plane parallel to said second plane. 5. The apparatus according to claim 1, wherein said second projection screen is a rear projection screen and said second projection means is a rear projection means wherein the images are electrically reversible. 6. The apparatus according to claim 1, wherein said second projection screen is a rear projection screen, said apparatus further comprises a full silvered mirror parallel to said partially silvered mirror, and wherein images from said second projection means are projected on said full silvered mirror and then projected on said second projection screen. 7. The apparatus according to claim 1, wherein said means of alternating between images from said projection means comprises image dissolve means. 8. A method of providing one or more selected visual illusion effects, comprising: (a) providing an apparatus comprising: (i) a rear projection screen having a front viewing side and being positioned in a first plane; (ii) a viewing area from which persons in an audience may view said rear projection screen; (iii) a stage area between said viewing area and said rear projection screen; (iv) an inclined, partially silvered mirror between said viewing area and said stage area, said mirror being inclined upward away from the viewing area; (v) a second projection screen lying in a second plane at an angle to said first plane, wherein said inclined mirror is positioned between said and at equal angles to first plane and said second plane; (vi) a first projection means for projecting images on said rear projection screen so that images on said rear projection screen are visible to viewers in said viewing area; (vii) a second projection means for projecting images on said second projection screen so that images on said second projection screen are visible to said viewers by means of reflection from said mirror and appear to be located at a selected location; and (viii) a means of changing between images from said projection means; (b) placing an object between said partially silvered mirror and said first screen; and (c) utilizing said projection means to create a visual illusion, associated with said object, at an apparent location, said apparent location selected from the group consisting of (i) a location in front of images on the rear projection screen; (ii) a location behind images on the rear projection screen; and (iii) a non- visible location. 9. The method according to claim 8, wherein said optical illusion effects comprise making a character or object located on said stage area not be visible to persons in said viewing area, said apparatus further comprises an illumination system for said stage area for illumination of objects on said stage at a desired light level without directly illuminating said first screen; and said method further comprises illuminating said character or object when images are projected from said first projection means, and ceasing illumination of said character or object when images are projected from said second projection means. 10. The method according to claim 8, further comprising moving said second projection screen to a plane parallel to said second plane resulting in a change in the apparent location of images on said second projection screen with respect to images on said first projection screen. 11. The method according to claim 10, further comprising providing a character in a production utilizing said apparatus with a position sensor device. 12. The method according to claim 11, further comprising linking said position sensor device with graphic illustration means which are visible on at least one of said projection screens. 13. The method according to claim 12, wherein said graphic illustration means results in an animated image which appears to be on a plane in space between said first plane and the viewing area. 14. A method of achieving visual merger of stage and screen images, comprising: (a) providing a viewing area for positioning viewers to view a live stage production, a stage area and a rear projection screen visible from said viewing area, a second projection screen not visible from said viewing area, stage lighting means, a partially silvered mirror between said viewing area and said projection screen, a first projection means for projecting an image on said projection screen and a second projection means for projecting an image on said second projection screen so that the image is reflected from said mirror, and a position sensor; wherein viewers in said viewing area cannot tell whether images being viewed are being reflected on said mirror or being projected on said rear projection screen; and (b) providing moving picture images, which are visible to viewers in the viewing area, utilizing either of the projection means so that an object or actor on the stage area appears to change between being included among the moving picture images, being transparent to a chosen degree, being invisible, being on the stage separate from the moving picture images, and interacting with the moving picture images through coordination of the degree of transparency of the object or actor with the appearance and disappearance of images in the moving picture, by coordinated selective use of said projection means, said lighting means and said position sensor. 15. The method according to claim 14, wherein the first projection means is utilized to provide the moving picture images. 16. The method according to claim 14, further comprising moving said second projection screen resulting in a change in the apparent location of images on said second projection screen with respect to images on said first projection screen. 17. An apparatus for providing visual illusion effects, comprising: (a) a first screen which is a rear projection screen, has a front viewing side, and is positioned in a first plane; (b) a viewing area from which area persons in an audience may view said first screen; (c) a stage area between said viewing area and said first screen, wherein images on said first screen are visible to persons in said viewing area; (e) a first inclined, partially silvered mirror between said viewing area and said first screen; (f) a second screen not visible from said viewing area and being movable between a plurality of second parallel positions so that a second series of images on said second screen is visible to said persons due to reflection of said second series of images from said first mirror, wherein said second series of images appears to said persons to be located at a selected location which is determined by the position of said second screen; (g) an image production system for selectively placing images on said first screen and said second screen; (h) an illumination system for said stage area for selective illumination of objects located on said stage area; (i) a computer-controlled switching apparatus for selectively activating said image production system and said illumination system, and for causing said second screen to move; wherein objects and actors actually located on said stage area may be made to appear more or less transparent and to be located in different locations with respect to each other and said first screen and said viewing area, by synchronized coordination of: (i) movement of said second screen, (ϋ) selective production of series of images, and (iii) activation of said illumination system; and wherein objects may be made to disappear completely or be transparent by aligning the screens to be equidistant from and at the same angle from the first mirror. 18. The apparatus of claim 17, wherein said images are moving images. 19. The apparatus of claim 17, further comprising a second mirror positioned so that images on said second screen are reflected in said second mirror and then on said first mirror. 20. The apparatus of claim 17, further comprising a third screen not visible from said viewing area and being movable between a plurality of third parallel positions, wherein said image production system also may be selectively activated to place images on said third screen, so that a third series of images on said third screen is visible to said persons in said audience due to reflection from said first mirror, and appears to be located at a selected location which is determined by the position of said third screen relative to said mirror, wherein said switching apparatus also selectively causes said third screen to move. 21. An apparatus for providing visual illusion effects, comprising: (a) a first screen which is a rear projection screen, has a front viewing side, and is positioned in a first plane; (b) a viewing area from which persons in an audience may view images on said first screen; (c) a stage area between said viewing area and said first screen; (d) a first inclined, partially silvered mirror between said viewing area and said first screen; (e) a second inclined, partially silvered mirror; (f) a second screen not visible from said viewing area and movable between a plurality of second parallel positions so that a second series of images on said second screen is visible to said persons in said viewing area when said second series of images is reflected on said second mirror and then reflected on said first mirror, wherein said second series of images appears to said persons to be located at a selected location which is determined by the position of said second screen; (g) a third screen not visible from said viewing area and being movable between a plurality of third parallel positions so that a third series of images on said third screen is visible to said persons when said third series of images is transmitted through said second mirror and reflected on said first mirror, wherein said third series of images appears to said persons to be located at a selected location which is determined by the position of said third screen; (h) an image production system, for selective production of: (i) a first series of images on said first screen so that said images are visible on said first screen to persons in said viewing area, and so that objects in said stage area do not cast shadows on said first screen; (ii) a second series of images on said second screen; and (iii) a third series of images on said third screen; (i) an illumination system for said stage area for selective illumination of stationary or moving objects located on said stage area; (j) a position sensor; and (k) a computer-controlled switching apparatus for selectively activating said image production system and said illumination system, and for activating the movement of said second and third screens; wherein objects and actors actually located on said stage area may be made to appear more or less transparent and to be located in different locations with respect to each other and said first screen and said viewing area, by synchronized coordination of: (i) movement of said second screen and said third screen, (ii) selective production of series of images, (iϋ) activation of said illumination system, and (iv) use of the position sensor. 22. The apparatus of claim 21, wherein said images comprise moving images. 23. The apparatus of claim 21, wherein said first screen is selectively movable between a plurality of first parallel positions in coordination with selective activation of said image production system and said illumination system and movement of said second screen and said third screen, to produce one or more selected effects visible to said person. 24. The apparatus of claim 21, further comprising a monitor screen to enable actors in said stage area to see the visual illusion effects which are visible to persons in said audience. 25. A method of providing one or more selected visual illusion effects, comprising: (A) providing an apparatus for providing visual illusion effects, comprising: (a) a first screen which is a rear projection screen, has a front viewing side, and is positioned in a first plane; (b) a viewing area from which persons in an audience may view images on said first screen; (c) a stage area between said viewing area and said first screen; (d) a first inclined, partially silvered mirror between said viewing area and said first screen; (e) a second inclined, partially silvered mirror; (f) a second screen not visible from said viewing area and movable between a plurality of second parallel positions so that a second series of images on said second screen is visible to said persons in said viewing area when said second series of images is reflected on said second mirror and then reflected on said first mirror, wherein said second series of images appears to said persons to be located at a selected location which is determined by the position of said second screen; (g) a third screen not visible from said viewing area and being movable between a plurality of third parallel positions so that a third series of images on said third screen is visible to said persons when said third series of images is transmitted through said second mirror and reflected on said first mirror, wherein said third series of images appears to said persons to be located at a selected location which is determined by the position of said third screen; (h) an image production system, for selective production of: (i) a first series of images on said first screen so that said images are visible on said first screen to persons in said viewing area, and so that objects and actors in said stage area do not cast shadows on said first screen; (ii) a second series of images on said second screen; and (iii) a third series of images on said third screen; (i) an illumination system for said stage area for selective illumination of stationary or moving objects or actors located on said stage area; (j) a position sensor; and (k) a computer-controlled switching apparatus for selectively activating said image production system and said illumination system, and for causing said second and third screens to move; wherein an apparent transparency and an apparent location, with respect to the location of said first screen and said viewing area, of each of said moving and stationary objects or actors, which are actually located on said stage area, are changeable by using said switching apparatus to cause coordination of: (i) movement of said second and third screens, (ii) selective activation of said image production system, (iii) activation of said illumination system, and (iv) use of said position sensor; (B) placing one or more objects or actors on said stage area between said partially silvered mirror and said first screen; and (C) utilizing said switching apparatus to coordinate movement of said screens, activation of said image production source to produce images on one or more selected screens in a determined sequence, and illumination of said objects and actors. 26. A method of achieving visual merger of stage and screen images, comprising: (a) providing a viewing area for positioning persons in an audience to view a live stage production; a stage area; a movable rear projection screen visible from said viewing area; at least one additional movable screen not visible from said viewing area; stage lighting means; an inclined, partially silvered mirror between said viewing area and said rear projection screen; a position sensor; and an image production system for selectively producing images on said rear projection screen, and on said additional screens so that said images are reflected from said mirror, wherein persons in said viewing area cannot tell whether images being viewed are being reflected on said mirror or being projected on said rear projection screen; and (b) providing moving picture images, which are visible to said persons in the viewing area, utilizing said image production system so that an object or actor on the stage area appears to said persons to change between being included among the moving picture images, being transparent to a chosen degree, being invisible, being on the stage separate from the moving picture images, and interacting with the moving picture images, through coordination of the degree of apparent transparency of the object or actor with the appearance and disappearance of images in the moving picture, by coordination of: (i) movement of said screens, (ii) selective production of series of images, (iii) activation of said illumination system, and (iv) use of said position sensor.

Inventors: BEAVER ROBERT T, BEAVER, ROBERT, T.
Applicants: BEAVER ROBERT T, BEAVER, ROBERT, T.
Application year: 1994
Main classification: G02B27
IPC codes: A63J5, G02B27